import { saveAs } from 'file-saver'
import { utils, SSF, write, BookType } from 'xlsx'

function generateArray(table) {
  const out: any[] = [];
  const rows = table.querySelectorAll('tr');
  const ranges: any[] = [];
  for (let R = 0; R < rows.length; ++R) {
    const outRow: any[] = [];
    const row = rows[R];
    const columns = row.querySelectorAll('td')
    for (const cell of columns) {
      let colspan = cell.getAttribute('colspan');
      let rowspan = cell.getAttribute('rowspan');
      let cellValue = cell.innerText;
      if (cellValue !== '' && cellValue === +cellValue) {
        cellValue = +cellValue;
      }
      // Skip ranges
      ranges.forEach((range) => {
        if (R >= range.s.r && R <= range.e.r && outRow.length >= range.s.c && outRow.length <= range.e.c) {
          for (let i = 0; i <= range.e.c - range.s.c; ++i) {
            outRow.push(null)
          }
        }
      })
      // Handle Row Span
      if (rowspan || colspan) {
        rowspan = rowspan || 1;
        colspan = colspan || 1;
        ranges.push({
          s: {
            r: R,
            c: outRow.length
          },
          e: {
            r: R + rowspan - 1,
            c: outRow.length + colspan - 1
          }
        });
      };

      // Handle Value
      outRow.push(cellValue !== '' ? cellValue : null);

      // Handle Colspan
      if (colspan) {
        for (let k = 0; k < colspan - 1; ++k) {
          outRow.push(null)
        }
      }
    }
    out.push(outRow);
  }
  return [out, ranges];
};

function datenum(v, date1904 = null) {
  if (date1904) {
    v += 1462
  }
  const epoch = Date.parse(v);
  return (epoch - (new Date(Date.UTC(1899, 11, 30)) as any)) / (24 * 60 * 60 * 1000);
}

function sheet_from_array_of_arrays(data) {
  const ws = {};
  const range = {
    s: {
      c: 10000000,
      r: 10000000
    },
    e: {
      c: 0,
      r: 0
    }
  };
  for (let R = 0; R !== data.length; ++R) {
    for (let C = 0; C !== data[R].length; ++C) {
      if (range.s.r > R) {
        range.s.r = R;
      }
      if (range.s.c > C) {
        range.s.c = C;
      }
      if (range.e.r < R) {
        range.e.r = R;
      }
      if (range.e.c < C) {
        range.e.c = C;
      }
      const cell: any = {
        v: data[R][C]
      };
      if (cell.v == null) {
        continue
      };
      const cellRef = utils.encode_cell({
        c: C,
        r: R
      });

      if (typeof cell.v === 'number') {
        cell.t = 'n'
      } else if (typeof cell.v === 'boolean') {
        cell.t = 'b'
      } else if (cell.v instanceof Date) {
        cell.t = 'n';
        cell.z = (SSF as any)._table[14]
        cell.v = datenum(cell.v);
      } else {
        cell.t = 's'
      }

      ws[cellRef] = cell;
    }
  }
  if (range.s.c < 10000000) {
    ws['!ref'] = utils.encode_range(range)
  }
  return ws;
}

class Workbook {
  public SheetNames: any[] = [];
  public Sheets: any = {};
}

function s2ab(s) {
  const buf = new ArrayBuffer(s.length);
  const view = new Uint8Array(buf);
  for (let i = 0; i !== s.length; ++i) {
    // tslint:disable-next-line: no-bitwise
    view[i] = s.charCodeAt(i) & 0xFF
  }
  return buf;
}

export function export_table_to_excel(id) {
  const theTable = document.getElementById(id);
  const oo = generateArray(theTable);
  const ranges = oo[1];

  /* original data */
  const data = oo[0];
  const wsName = 'SheetJS';

  const wb = new Workbook()
  const ws = sheet_from_array_of_arrays(data);

  /* add ranges to worksheet */
  // ws['!cols'] = ['apple', 'banan'];
  ws['!merges'] = ranges;

  /* add worksheet to workbook */
  wb.SheetNames.push(wsName);
  wb.Sheets[wsName] = ws;

  const wbout = write(wb, {
    bookType: 'xlsx',
    bookSST: false,
    type: 'binary'
  });

  saveAs(new Blob([s2ab(wbout)], {
    type: 'application/octet-stream'
  }), 'test.xlsx')
}

export function export_json_to_excel({
  multiHeader = [],
  header,
  data,
  filename,
  merges = [],
  autoWidth = true,
  bookType = 'xlsx'
} = { header: {}, data: [] as any[], filename: '' }) {
  /* original data */
  filename = filename || 'excel-list'
  data = [...data]
  data.unshift(header);

  for (let i = multiHeader.length - 1; i > -1; i--) {
    data.unshift(multiHeader[i])
  }

  const wsName = 'SheetJS';
  const wb = new Workbook()
  const ws = sheet_from_array_of_arrays(data);

  if (merges.length > 0) {
    if (!ws['!merges']) {
      ws['!merges'] = []
    }
    merges.forEach((item) => {
      ws['!merges'].push(utils.decode_range(item))
    })
  }

  if (autoWidth) {
    /*设置worksheet每列的最大宽度*/
    const colWidth = data.map((row) => row.map((val) => {
      /*先判断是否为null/undefined*/
      if (val == null) {
        return {
          wch: 10
        };
      } else if (val.toString().charCodeAt(0) > 255) { /*再判断是否为中文*/
        return {
          wch: val.toString().length * 2
        };
      } else {
        return {
          wch: val.toString().length
        };
      }
    }))
    /*以第一行为初始值*/
    const result = colWidth[0];
    for (let i = 1; i < colWidth.length; i++) {
      for (let j = 0; j < colWidth[i].length; j++) {
        if (result[j].wch < colWidth[i][j].wch) {
          result[j].wch = colWidth[i][j].wch;
        }
      }
    }
    ws['!cols'] = result;
  }

  /* add worksheet to workbook */
  wb.SheetNames.push(wsName);
  wb.Sheets[wsName] = ws;

  const wbout = write(wb, {
    bookType: bookType as BookType,
    bookSST: false,
    type: 'binary'
  });
  saveAs(new Blob([s2ab(wbout)], {
    type: 'application/octet-stream'
  }), `${filename}.${bookType}`);
}
